Due to cost, many lasers do not have built-in heaters or coolers. Unless an internal thermoelectric heater/cooler is included, the case temperature of an operating laser is substantially equivalent to ambient temperature. In some cases, for example outdoor HFC applications such as CATV nodes, the case temperature can be quite extreme. Outside temperatures may reach as cold as −40 degrees Celsius.
Moreover, laser performance characteristics are very dependent upon operating case temperature. Not only do parameters such as slope efficiency and output power vary with operating temperature, but output wavelength varies as well. This can cause issues if the laser output wavelength drifts outside of the bandwidth of the combining and splitting optical passives in the network. Therefore, it is desirable to maintain the laser at as constant a temperature as possible or at least within a range that the device is designed to operate within. What is needed is an economical means to minimize performance degradation due to cold temperatures and to extend the lowest temperature a laser can operate at.